This 2-year Phase I SBIR Application centers on completing the lead optimization of an ultra-broad-spectrum carbapenem (UBSC) lead series with an unprecedented antibacterial spectrum of activity including MRSA, Enterobacteriaceae and Pseudomonas aeruginosa. At the completion of lead optimization, the resulting Preclinical Development Candidate will be paired with a proprietary in-house -lactamase inhibitor (BLI) to protect against resistance by Ambler Class A, B and D carbapenemase-producing Gram negatives. Further advancement through IND-enabling preclinical studies will be proposed in the Phase II SBIR stage. Ultimately, it is envisioned that this new combination product will provide a unique clinical option for empiric therapy of multi-drug resistant polymicrobial infections in the hospital general ward and ICU, and as a second line therapy for susceptible organisms.